Any interest in a transverter for the LOW bands?

[VK3XDK]

Gday all,
Many may have missed my post (in "First 630 metre contacts")
Im considering making a transverter available for these very low bands.

There is quite a bit of work involved. Although interested myself I wont bother designing an available Kit/board unless others are going to be interested.
Im thinking towards a selective and good dynamic range receiver strip (to cope with adjacent broadcast) and around 1W TX strip (iF there is enough interest i could design a second higher power tx stage in the future (many many be able to do it themselves?))

As most are (or will become aware) our "commercial" transceivers fall very short when it comes to both RX and TX on these low bands.

I really dont need the extra work, but it may be a "goer" if I get enough interest!

cheers, Graham VK3XDK

http://www.vk3xdk.net46.net/

[VK4TI]

Gday all,
Many may have missed my post (in "First 630 metre contacts")
Im considering making a transverter available for these very low bands.

There is quite a bit of work involved. Although interested myself I wont bother designing an available Kit/board unless others are going to be interested.
Im thinking towards a selective and good dynamic range receiver strip (to cope with adjacent broadcast) and around 1W TX strip (iF there is enough interest i could design a second higher power tx stage in the future (many many be able to do it themselves?))

As most are (or will become aware) our "commercial" transceivers fall very short when it comes to both RX and TX on these low bands.

I really dont need the extra work, but it may be a "goer" if I get enough interest!

cheers, Graham VK3XDK

http://www.vk3xdk.net46.net/

SO any idea of the basic cost to get that 1w ?. which band as an if ?
certainly an interesting idea and does it come with a shrinking potion so my 40 m vetical antenna works efficiently down there by growing electrically ?

[VK5PJ]

Hi Graham,
it might be worth considering an ex CB tranceiver as the IF, these are in plentifull supply and usually have good stability and sensitivity, even the IF strip of one of these radios would be a good building block and allow us to re-cycle the 11 metre radios sitting in cupboards around VK.

This then means the is no need to tie up the normal HF rig on LF duties.

my 2 cents.

Peter, vk5pj

[VK5ACY]

I would like a transverter, I have wanted to play with LF since I have been at this low-noise location.

...and there's a 40 channel SSB CB rig in my 'junk room'..and I reckon it has a good noise blanker..

[VK3XDK]

Thanks for the first few replies,
I think the final cost will be less the $60. (depending on the price of tunable inductors, for good "bandpass" response)

Reply to the "cb" notion, I think that most of us have a far better "IF" (our own amateur radio) that can be used easier and in general are far better than any CB! (and we should already have one)

I think that (for those that understand transverters) a 10Mhz IF is a good choice! (ie, 10mhz LO (is easily available, can be easily GPS locked (for those more serious)and cheap)
SO 10.472Mhz TX/RX (on our 10Mhz band) becomes 472Khz (10.472Mhz-10Mhz= 472Khz) and 10.479 TX/RX (on our 10Mhz band) becomes 479Khz(10.479-10Mhz=479Khz) due to the "transverter process"

As much as I would like to make the output power higher, I think that a modular form would be easier for most and much easier to fault-find if there happens to be a problem.(My kits are normally built by the user)
the "KISS" (keep it simple silly) approach will help the builder (and me! if there's a problem (I normally offer follow up assistance, within reason))
1watt would be a very good start (low level transverter) Enough power to drive a much higher power PA (at these frequencies)

graham, VK3XDK

[VK3XDK]

I should also add,
this will be a "bare bones' board, it will need to be mounted in a box and it is up to the constructor to add t/r switching (normally just a relay or two to suit their rig), An understanding of "transverters" will be necessary!

I dont favour helping those that are in too deep

[VK4WDM]

I would definitely be interested especially if it could be run off my FT-817ND for portable use. The only problem I would have is the SMD components - the eyesight is not what it used to be. One way round that would be to get construction as a club project. Then the well-sighted young ones could help the geriatrics.

Given the age of our club population and the percentage of pensioners, cost would be an issue. Something less than $100 would be ideal.

I will float the idea at our next cliub meeting.

73

Wayne VK4WDM

[VK4TI]

I should also add,
this will be a "bare bones' board, it will need to be mounted in a box and it is up to the constructor to add t/r switching (normally just a relay or two to suit their rig), An understanding of "transverters" will be necessary!

I dont favour helping those that are in too deep

Sounds like an excellent beginning , for more power a simple mosfet amp based on audio devices should be very possible just like the 160 M amps built all over , I raises me hand for interest indeed .

[VK3ALB]

I think that (for those that understand transverters) a 10Mhz IF is a good choice! (ie, 10mhz LO (is easily available, can be easily GPS locked (for those more serious)and cheap)
SO 10.472Mhz TX/RX (on our 10Mhz band) becomes 472Khz (10.472Mhz-10Mhz= 472Khz) and 10.479 TX/RX (on our 10Mhz band) becomes 479Khz(10.479-10Mhz=479Khz) due to the "transverter process"

A logical place to start but it's possible that not all radios that have 30m capabilities can transmit on 10.472. An FT817 would be a logical choice for the IF radio but it cannot transmit on that frequency. I tried two other Kenwood radios with the same result.

[VK3YE]

I may but only if my own homebrew attempts don't work. Also undecided whether I go the CW transmitter + rx converter or transverter route.

I think it's desirable that it's able to be teamed up with the FT-817 given that many will try portable operating to get a better antenna up/quieter spot. Hence I'd suggest a board design that suits a case the same width as the 817.

Another feature I'd recommend and would give it an edge over others would be the option of two antenna sockets. One for efficient Tx antenna and one for low noise Rx antenna. Along with switching to receive on the Tx antenna if using just one. This is up to the builder as it's a short-form kit but some board provision may be required if the relays were going to be on the circuit board.

[VK2GOM]

Same on my IC7600. It won't Tx beyond the 30m band edge, as I'd expect.

In fact, I doubt any modern rig designed for the VK market would.

Isn't there another choice of IF that would work? Is up on 28MHz too high?

73 - Rob VK2GOM / GW0MOH

[VK3AIF]

Count me in Graham and 1 watt will be fine as I have a vt4c here looking for something to do, that should get me somewhere near the 5w eirp. I like the idea of provision for a separate RX input as well although that should not be too hard for anyone to configure anyway.

[VK3XDK]

Are most new-er transceivers capably of TXing on 10.479Mhz? Mine are, I assumed.
I can design a board that will work even lower but not sure about coils that fit. In my initial research, tunable caps are not feasible- tunable coils are the option. (its all about resonance!especially with narrow bandwidth/selectivity)

There could be more than 1Watt, Im just not over-committing myself (DC is new to me ) Im looking at component and heat-sinking requirements.

Sorry about SMD (for those that are aging)
Unfortunately (or fortunately) smd are far superior in most ways(especially as we get higher in frequency) (the best components are heading to be only available that way). They also tend make an easier to follow pcb (gnd only on bottom side of pcb)
I also found them hard at first but they get bigger as you use them.(I or others can sometimes help)
I use them 95% and recommend them to even the most stubborn! I and most with practice will never go back.

[VK3XDK]

The IF can be anywhere (within reason) but must be accessible with IF and LO availability.
In fact a transverter designed for a 10Mhz LO can be used anywhere with just a change of LO (472khz + LO (of your choice) = IF (of your choice)) the initial filtering/board will still perform the same.
I choose 10Mhz due to convenience.

Some people turn up everywhere (VK3ALB, VK2DAG!) (thought you fella's were busy with the microwaves?)

[VK4WDM]

The G3XBM transverter for his FT-817ND uses an 80m IF, but as you say Graham, that makes the tuning components bigger.

I will have a go at the SMD's I guess we can have have a few spares included at an increased price in case we fry them, or drop them on the shack floor.

73

Wayne VK4WDM

[VK3XDK]

The IF can be anywhere (within reason) but must be accessible with IF and LO availability.
In fact a transverter designed for a 10Mhz LO can be used anywhere with just a change of LO (472khz + LO (of your choice) = IF (of your choice)) the initial filtering/board will still perform the same.
I choose 10Mhz due to convenience.

Some people turn up everywhere (VK3ALB, VK2DAG!) (thought you fella's were busy with the microwaves?)

[VK3XDK]

The IF can be anywhere (within reason) but must be accessible with IF and LO availability.
In fact a transverter designed for a 10Mhz LO can be used anywhere with just a change of LO (472khz + LO (of your choice) = IF (of your choice)) the initial filtering/board will still perform the same.
I choose 10Mhz due to convenience.

Some people turn up everywhere (VK3ALB, VK2DAG!) (thought you fella's were busy with the microwaves?)

[VK4GHZ]

(VK3ALB, VK2DAG!) (thought you fella's were busy with the microwaves?)

Fringe dwellers!

[VK4TI]

Are most new-er transceivers capably of TXing on 10.479Mhz? Mine are, I assumed.
I can design a board that will work even lower but not sure about coils that fit. In my initial research, tunable caps are not feasible- tunable coils are the option. (its all about resonance!especially with narrow bandwidth/selectivity)

There could be more than 1Watt, Im just not over-committing myself (DC is new to me ) Im looking at component and heat-sinking requirements.

Sorry about SMD (for those that are aging)
Unfortunately (or fortunately) smd are far superior in most ways(especially as we get higher in frequency) (the best components are heading to be only available that way). They also tend make an easier to follow pcb (gnd only on bottom side of pcb)
I also found them hard at first but they get bigger as you use them.(I or others can sometimes help)
I use them 95% and recommend them to even the most stubborn! I and most with practice will never go back.

http://www.classeradio.com/24_fet.htm explains about dc , the mosfets used are dirt cheap not that I suggest you use them

[VK4WDM]

They just want the chance to play with BIG things, BIG capacitors, BIG coils, BIG (or at least FAT) antennas.

It is interesting how a new band with new challenges, and no ready-made rigs in the offing gets the ham primeval juices running. 2200m did not seem to have the same effect, I guess it is just too far from the traditional ham bands and requires specialized techniques (but a transverter would be good for that band too Graham) whereas 600m shares some characteristics with 160m.

To me 600m seems more like "real ham radio" than microwaves (had to put some sort of controversial comment in).

73

Wayne VK4WDM

(Yes I have got the cake of soap ready to wash my mouth out).